IcculusNews is a Perl-based daemon that sits on port 263 (by
default). It is used for many sites, including icculus.org itself.
IcculusNews can output headlines streams. It also has a GTK+(2)
interface (screenshot),
and a library for other client access. There is also a php/web-based
interface integrated without libinews.

You can check out IcculusNews from Mercurial via these simple
instructions:

hg clone http://hg.icculus.org/icculus/icculusnews/

IcculusNews is currently lacking in documentation, however, the
protocol is documented in protocol.txt